Evaluating the Effect of Crutch-Using on Trunk Muscle Loads

Jing Chang, Wenrui Wang, Damien Chablat, Fouad Bennis

Abstract: Crutch is the most common tool for temporary or permanent ambulation assistance. Crutch-using transforms human kinematic chain, and therefore is hypothesized to have dynamical influence on the trunk. In this paper, two different crutch gaits were analyzed with regard to their associated risks of scoliosis. A numerical human-crutch model was constructed on the OpenSim software, then both unilateral crutch gait (denoted as single crutch walking) and bilateral crutch gait (denoted as double crutch walking) were simulated to represent the situation where ones’ right foot gets injured and bears 10% of body weight at most. The kinematics of one single moment in the weight-transferring phase were constructed through joint space. The inverse dynamics calculation and the static optimization algorithm were conducted to compute joints load and muscles activation level at this moment. Attentions were paid to eight muscle groups that are closely associated with the occurrence of scoliosis. As the results, the average muscle activation level of the eight muscle groups were 31% in the case of single crutch walking and 9% for the double crutch walking, as compared with 1% in a normal gait. Muscle activation asymmetry was more severe for single crutch gait than that of a double crutch gait. It is suggested that the unilateral crutch walking brings higher risk of scoliosis than the bilateral crutch walking in the partial weight bearing gaits.